Naphtha catalytic cracking for light olefins production over cyclic regenerative process with dry gas diluent

Abstract

A method of producing olefins by catalytic cracking of hydrocarbons is disclosed. The method may include catalytic cracking hydrocarbons in a feed stream that includes the hydrocarbons and the dry gas diluent. The catalytic cracking may be carried out in a process using a train of fixed bed reactors while one or more other trains of fixed bed reactors are being regenerated or are on standby after being regenerated. When the train of fixed bed reactors being used needs regenerating, it is taken out of service and the one or more other trains of fixed bed reactors put in service to carry out the catalytic cracking process. Dry gas instead of steam may be used to reduce the partial pressure of hydrocarbons.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a national phase application under 35 U.S.C. § 371 of International Application No. PCT / IB2017 / 057797 filed Dec. 11, 2017, which claims priority to U.S. Provisional Patent Application No. 62 / 433,618 filed Dec. 13, 2016. The entire contents of each of the above-referenced disclosures is specifically incorporated by reference herein without disclaimer.FIELD OF INVENTION[0002]The present invention generally relates to the production of light olefins. More specifically, the present invention relates to the catalytic cracking of liquid hydrocarbons to form light olefins.BACKGROUND OF THE INVENTION[0003]Distilling crude oil to produce products such as butane (or lighter hydrocarbons), straight run gasoline, naphtha, kerosene, light gas oil, heavy gas oil, and straight run residue is simply separating the crude oil into its various constituents. Thus, under set processing conditions, the relative proportions of the products p...

AI Technical Summary

Benefits of technology

[0007]A discovery has been made of a process that addresses the foregoing problems associated with the catalytic cracking of hydrocarbons to form light olefins. Embodiments of the process involve alternately utilizing one of at least two trains of fixed bed reactors to catalytically crack hydrocarbons in a feed mixture that includes the hydrocarbons and dry gas. In this way, a continuous process involving cyclic regeneration of catalyst is provided, where minimal catalyst makeup is required because the dry gas serves as a diluent that minimizes coke formation and reduces catalyst structural damage.

Problems solved by technology

As a result of the coke deposits on the catalyst, the catalyst becomes less effective or inactive—that is, the catalyst becomes spent.

However, carrying out this conversion with high selectively and high yields poses a challenge from both process configuration and catalyst design standpoints.

In addition, at such high temperature, catalyst deactivation is problematic; specifically, catalysts in this process deactivate more frequently than some other catalytic processes.

Catalyst deactivation is caused by coke formation and structural damage of the catalyst caused, at least in part, by high temperatures.

The process suffers from heat imbalance when paraffinic feed is used.

The amount of coke is not enough to sustain the energy balance.

In addition, the process requires high catalyst / oil ratio in order to have acceptable yields and requires continuous catalyst make up as a result of rapid loss of catalyst activity.

In the ACO™ process, yields per pass are relatively low compared to a fixed bed process because of the short residence time of the process.

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